The present invention relates to the art of color proofing, and in particular, to a laminator member for preparing prepress color proofs. More particularly, this invention relates to an improved lamination member that includes a new reinforcing fluorocarbon silane coupling reagent additive.
Prepress color proofing is a procedure that is used by the printing industry for creating representative images of printed material to check for color balance and other important image quality control parameters, without the high cost and time that is required to actually produce printing plates and set up a printing press to produce an example of an intended image. These intended images may require several corrections and may be reproduced several times to satisfy or meet the requirements of the customers, resulting in a large loss of profits and ultimately higher costs to the customer.
Generally speaking, color proofs sometimes called xe2x80x9coff pressxe2x80x9d proofs or prepress proofs, are one of three types: namely (1) a color overlay that employs an image on a separate base for each color; (2) a single integral sheet process in which the separate color images are transferred by lamination onto a single base; and (3) a digital method in which the images are produced directly onto or transferred by lamination onto a single base from digital data.
In one typical process for a prepress color proofing system used in the printing industry, a multicolor original is separated into individual transparencies, called color separations, the three subtractive primaries and black. Typically a color scanner is used to create the color separations and in some instances more than four-color separations are used. The color separations are then used to create a color proof sometimes called an xe2x80x9coff pressxe2x80x9d proof or prepress proof as described above.
A KODAK Color Proofing Laminator can be used to bond lamination sheets to receiver stock as a part of a color proofing system. The lamination sheets include a carrier and a layer of material to be applied to the receiver stock, which, in the case of the Kodak Color Proofing Laminator, is a color donor. A lamination sheet is laid upon the receiver stock with the color donor side sandwiched between the carrier and the receiver stock forming a lamination sandwich.
FIG. 1 in U.S. Pat. No. 5,478,434 shows a laminator 12. As shown in that FIG. 1, a lamination sandwich 10 sits on an entrance table 20. A leading edge of lamination sandwich 10 is fed into a laminator 12 which includes an upper heated pressure roller and a lower heated pressure roller. Lamination sandwich 10 passes completely through the upper heated pressure roller and the lower heated pressure roller. Lamination sandwich 10 thereafter exits the upper heated pressure roller and the lower heated pressure roller and comes to rest on an exit table 14 undisturbed until the trailing edge is cool to the touch; whereupon the top-most carrier can be peeled away from receiver stock and from the transferred color donor. With the configuration of an upper heated pressure roller and a lower heated pressure roller as described above, the laminator is called a straight-through laminator. Further details of this type of lamination/de-lamination system can be found in the above. As an additional reference, U.S. Pat. No. 5,203,942 describes a lamination/delamination system as applied to a drum laminator.
U.S. patent application Ser. No. 09/133,243, abandoned, provides for belt roller arrangement which applies a tapering pressure to a lamination sandwich (hereinafter referred to as media to be laminated), and conveys the media to be laminated to a nip portion between heated pressure rollers. The belt materials used are either metal or thermoplastics. In addition, the belts need to survive cycled heat and pressures and preferably, to be a seamless polyimide belt. However, the high surface energy of the polyimide belts pickup dirt, dusts or contamination from the media. The polyimide belt failed to release the media during usage. There is a need for an overcoat with desired heat resistance and release properties.
U.S. patent application Ser. No. 08/782,899 U.S. Pat. No. 5,948,491 describes an improved toner fuser member and new adhesion priming composition which improve the adhesion between the fluoropolymer and the epoxy substrate. However, it leaves unsolved the problem of adhesion between PTFE and the organic polymer binder.
One commercially available polymer for lamination belt overcoat is polytetrafluoroethylene (PTFE) dispersion from Whitford. This overcoat provides a low surface energy surface to help release the media. However, within few hours of heating and pressure under normal usage, a white flake built up on the surface and image artifacts occurred. Also, a noticeable loss of release properties was observed. It is believed the PTFE could not hold within the overcoat. There is a need for an additive to reinforce the integrity of the overcoat.
In accordance with the present invention, there is disclosed a laminator member for color proofing comprising a belt substrate and a surface layer, said surface layer comprising a polyamide-imide organic polymer binder; a fluorinated resin polymer; and a perfluoroalkylsubstituted fluororesin-reactive compound having the formula: 
where R5 is H or F; Q is OH, SiR6R7R8; R6, R7, and R8 being independently selected from the group consisting of Cl, OH, an alkyl group containing 1 to about 4 carbon atoms, an alkoxy group containing 1 to about 4 carbon atoms, an acyloxy group containing 2 to about 4 carbon atoms, and an amino group containing 0 to about 4 carbon atoms; and n is an integer from 1 to about 15; with the proviso that, at least one of R6, R7, and R8 is Cl, OH, or an alkoxy, acyloxy, or amino group; and wherein said surface layer is adhered to said belt substrate by the polyamide-imide polymer binder.
The laminator member of the invention comprises a substrate to which is adhered a surface layer comprising PTFE in the form of small particle slurry before coating. The lamination substrate comprises polyimide in the shape of a cylinder or, preferably, a seamless belt. The PTFE particles are bonded by a organic polymer binder. The organic polymer binder is polyimide-amide as described in the above formula. Polyamide-imide priming agent can be prepared by the method taught by U.S. Pat. No. 4,087,394.
The additive in the present invention interacts with both the organic polymer binder and the PTFE particles. It also improves the binding between the PTFE and the polyimide substrate due to the dual functionality of the coupling reagent. The lamination belt member with the present invention is characterised by good release and excellent integrity of the overcoat during the life of the belts.